1. Field of the Invention
This invention relates to a coin-shaped integrated circuit memory device in which a non-volatile memory chip is housed, and on an outer peripheral side portion of which write protect means is provided for preventing data from being written in the memory chip.
2. Description of the Related Art
An IC card is basically constructed by sealing an IC module housing an IC memory chip in a core member, and is formed to have the same size as a credit card having a magnetic record member, i.e., it has a size of 54 mm (width).times.85.5 mm (length).times.0.8 mm (thickness). The IC card further has a control circuit element for identifying its owner, in addition to a memory circuit element, so that it is distinguished from the memory card only with a memory function.
Memory cards are widely used in digital electronic devices such as electronic calculators, word processors, pocket computers, and electronic notebooks, etc. The memory card used in the digital electronic devices generally has the same size as the IC card, i.e., 54 mm.times.85 mm. However, it is thicker than the IC card, and hence the rigidity of the entire memory card is greater than the IC card. Further, there is a memory card which is half in size in comparison with the IC card. This memory card is, however, too large to be applied to a wrist watch-type electronic device. Since the wrist watch-type electronic device is portable, it would be very convenient for carry if the device has such functions as the above-described electronic calculator, word processor, pocket computer, and electronic notebook. In order to make compact the wrist watch type electronic device, it is preferable that a memory card to be employed therein is shaped like a coin or thin disk to accord with the shape of the device.
Further, in order to be received in such a small wrist watch type device, a coin-shaped integrated circuit memory device must have such a small size of 10 mm-20 mm (diameter).times.1 mm-2 mm (thickness). A merely small integrated circuit memory device can be easily obtained by using a flip chip bonding method in which an integrated circuit memory chip obtained by dicing a wafer is directly bonded to a circuit substrate. An IC module formed by this method is employed in the above-described IC card. However, since the rigidity of the IC module is secured by a card-shaped core member, a safe rigidity cannot be obtained when the IC module is singly mounted in a device. In addition, since writing and reading data in and from an IC module incorporated in the IC card is conducted under control of a host computer, so that an operator has no means to selectively operate the IC module. As regards an integrated circuit memory device to be mounted in a compact electronic device for a consumer, the memory device would not be useful at all if the user cannot selectively operate in a data-writing or a data-reading.